The net clinical benefit (NCB) of anticoagulants like warfarin and apixaban slows over time in patients with atrial fibrillation, according to a Circulation: Cardiovascular Quality and Outcomes study, diminishing as people age and face competing risks of death.
Clinical guidelines recommend anticoagulation for all AFib patients aged 75 years and up, first author Sachin J. Shah, MD, MPH, of the University of California, San Francisco, and colleagues wrote in the journal, and while that makes sense—aging increases the average person’s risk of ischemic stroke—there’s little evidence of a net clinical benefit in older patients.
“While anticoagulation effectively reduces the risk of ischemic stroke, it increases the risk of hemorrhagic events,” the authors said. “Importantly, the risk of hemorrhagic events also rises with age. Decision-making is complicated further because advancing age increases the likelihood of death from a non-AFib-related cause, thereby limiting the likelihood of actualized benefit or harm from AFib and anticoagulation.”
Shah et al. looked at 14,946 patients with incident AFib for their study, drawing data from the Anticoagulation and Risk Factors in Atrial Fibrillation-Cardiovascular Research Network registry. They estimated the lifetime NCB of warfarin and apixaban relative to no treatment in quality-adjusted life years (QALYs), defining minimal clinically relevant lifetime benefit as 0.10 QALYs.
The team’s study population was on average 81 years old and presented with a CHA2DS2-VASc score of 4. In their main analysis, after age 87, NCB associated with warfarin dropped below 0.10 lifetime QALYs, but NCB associated with apixaban didn’t dip below the same threshold until after age 92.
Three-year sensitivity analyses revealed that removing competing risks of death, like cancer or end-stage kidney disease, from the equation resulted in higher NCBs at 90 years—an average difference of 0.010 QALYs when using warfarin and an average difference of 0.025 QALYs when using apixaban.
Shah and colleagues said their results have “important implications” for the clinical care of older patients with AFib. Their study found that, just as current guidelines suggest, patients aged 75 years and up are likely to benefit from taking anticoagulants—but their NCB will also likely decrease every year after 75.
“Competing risks have an important influence on this declining net clinical benefit,” the authors wrote. “Clinicians should consider competing risks when discussing the potential benefit of anticoagulants with older adults with AFib. Future work should focus on incorporating competing risks into estimates of the net clinical benefit of anticoagulation and anticoagulation clinical decision aids.”